Heat pumps are a year-round comfort system that use refrigeration technology to supply warm air in the winter and cool air in the summer. The most common systems in Lewis County are Air source or “air-to-air” heat pumps. The two most common heat pump applications are ducted “central air” systems and ductless “mini-split” systems.

An air source heat pump has two parts, an indoor unit with a coil and a fan to push the air through your home; and an outdoor unit with another coil, another fan and a compressor. Heat pumps have the ability to use the indoor and outdoor unit as an evaporator or a condenser depending on the season, and whether the system is calling for heating or cooling. In the winter, the refrigerant absorbs heat from the outside air and with the help of the compressor, heats up the refrigerant. The warm refrigerant flows to the indoor unit where the fan pushes air over the coil, and as the air absorbs that heat, it is delivered into your home. In the summer, the process reverses. The refrigerant absorbs heat from the air inside your home, cooling the air delivered into your home and heating up the refrigerant. That warm refrigerant is sent through the outdoor coil and releases the heat to the outside air, cooling the refrigerant as it prepares to continue the cycle.

Heating season thermostat setting

When your home is occupied the recommended set point is 68˚, and every degree you increase your set point can cost an additional 2% – 4%.  Heat pumps work most efficiently when maintaining a temperature. Consequently, it is recommended to only lower your set point by 3˚ – 5˚ when your system is in the unoccupied or night setting. Most of today’s thermostats are programmable and allow you to set a schedule to match your preference. These thermostats allow the system to employ a “smart” feature which slowly increases the air temperature as it switches from the unoccupied or night setting to your occupied setting without bringing on the more expensive back up or “auxiliary” heat.

Cooling season thermostat setting

When your home is occupied the recommended setting is 78˚. The same set point variation principles apply to the cooling season and system efficiency. While you may not want to change your night set point during the summer, the recommended unoccupied setting is between 81˚ and 85˚.

Thermostats

There is now a variety of options available to consumers, all of which, can adequately control a heat pump system. Your selection should be based on your lifestyle and personal preference in control. Smart thermostats can automatically learn and set your schedule, utilizing an infrared sensor that senses movement in the home, and can be controlled remotely with a computer or smart phone when connected to your homes WiFi network.

There are more basic digital thermostats available. Some have the option of setting a schedule manually, while others are simply controlled by setting a temperature and system operation (heating or cooling).

The way you operate your chosen thermostat can greatly affect your systems efficiency. Avoid the urge to use your thermostat as a gas pedal. Temporarily using a higher or lower than needed setting in an attempt to bring the temperature up or down faster. This significantly increases the systems energy consumption and operating cost. It is best to set a schedule or temperature and allow the system to do the rest.

Filters

Filters should be checked each month and changed when dirty. The filter is an important part of your system tasked with cleaning the air that moves through the system. A filter that is allowed to accumulate too much dust and dirt will cause the fan to work harder and stay on longer. The other, and arguably more important function of the filter, is to keep dust off the indoor coil. When a layer of dust forms on your indoor coil, it has a much harder time absorbing or releasing heat to the air running across it, and will negatively affect the systems run time and energy consumption.

What is Auxiliary Heat? (Ducted Systems Only)

As discussed, heat pumps absorb heat from the outside air. The refrigeration cycle however cannot produce enough heat when the outdoor temperature drops below the systems designed balance point. The balance point is the outdoor temperature when the heat pump likely needs assistance in providing the necessary heat to satisfy the thermostat set point. In this case, the system automatically turns on the electric resistance portion of the indoor furnace. Depending on the size of your home and electric furnace, your system can be consuming anywhere from 3 to 5 times more power to heat your home during this time. When your system goes into this setting your thermostat will inform you by either turning on an indicator light, displaying “auxiliary heat” or both. This feature can be locked out by your installer until the outdoor temperature is below the designed balance point as long as the correct equipment is in place to control the system. The locking out of the auxiliary heat can be a big energy saver and is highly recommended. It is also a requirement when installing a heat pump through the Lewis County PUD residential heat pump program.

Emergency Heat (Ducted Systems Only)

Many homeowner misuse this setting more than any other. The Emergency Heat setting should only be used when the outdoor unit of your heat pump system is not working properly. This function allows the furnace to run independently of the outdoor unit and overrides the auxiliary heat lockout function until a technician can resolve the problem. If you switch your system to this setting just because it is cold outside, it will drastically increase the cost of heating your home.

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